Daisy Wells and Hazel Wong are best friends, schoolgirls - and detectives. And wherever Daisy and Hazel go, a mystery is sure to find them. On holiday at the seaside with their friends George and Alexander, they discover a body on the beach. They soon realise this is Antonia Braithwaite: a famous swimmer, nicknamed The Pearl, who was due to compete at the Berlin Olympics next month. It appears she has accidentally drowned in the sea - but it's odd that this should happen to such a strong swimmer. Even more mysteriously, she smells not of the sea, but of Pears soap. Rushing back to their elegant hotel, Daisy and Hazel discover three suspicious guests who all had reason to murder Antonia.